When I was about 8 or so, my horseback riding instructor took to calling me Suzzen, saying there was some rock star who went by that name. That got shortened to Suzz, and then one day she called me Sudz by mistake. For whatever reason, Sudz stuck, and that's been my nickname among family and close friends for a while now. (My parents hardly ever call me Susan, unless of course they're mad at me, which fortunately isn't very often now that I've passed those lovely teenage years.)
I quit broadcasting this as a nickname a few years back. I don't exactly introduce myself to business associates by saying, "Hello, I'm Susan. Please call me Sudz." I guess that's normal, to "outgrow" our childhood nicknames. It's certainly not something I'm embarrassed to be called, but it's not a nickname I'll specifically request new friends/acquaintances use.
Anybody else have any nicknames that are not at all or only tangentially related to your actual name?